AB0033 T- AND B-CELL SUBSETS AS ADDITIONAL DIAGNOSTIC TOOL FOR PRIMARY SJOGREN’S SYNDROME AND SYSTEMIC LUPUS ERYTHEMATOSUS
Authors: S. Benevolenskaya, I. Kudryavtsev, M. Maria, K. Serebriakova, A. Budkova, I. Grigor’eva, E. Kuvardin, S. Koniakhin, D. Zammoeva, D. Motorin, S. Lapin, A. Maslyanskiy
Journal: Annals of the Rheumatic Diseases (2022)

Background Systemic lupus erythematosus (SLE) and primary Sjogren’s syndrome (pSS) are chronic autoimmune diseases with complex pathogenesis. T-lymphosytes are known to be prime effectors of autoimmune diseases, while B-lymphosytes play a key role as sources of antibodies and antigen presenting cells. Considering the implications of T- and B-cells in the pathophysiology of SLE ans pSS, the assessment of their distribution in the blood could be helpful in the complex process of determining a precise diagnosis. Objectives The study aimed to compare composition of peripheral blood T- and B-cell subsets and investigate their diagnostic utility in patients with SLE and pSS. Methods The study was performed with 37 patients suffering from SLE, 57 patients with pSS, and 49 apparently healthy volunteers (HVs). The diagnosis of SLE was performed according to the 2019 EULAR – ACR classification criteria, the diagnosis of pSS- according to the 2016 EULAR – ACR criteria. 11 patients in pSS group met the criteria for both pSS and SLE. The relative distribution and percentage of T- and B-cell subsets were evaluated by flow cytometry. T helper (Th) and cytotoxic T-cell subsets (Tcyt) were identified by using CD3, CD4, and CD8 antibodies. Regulatory T cells (Tregs) were characterized by the expression of CD3, CD4, and high IL-2R alpha chain (CD25high) levels. All peripheral blood B-cells were identified by using CD19 antibody, detection of subpopulations of B cells based on expression of IgD, CD38, CD27. The absolute and relative values ​​of B-lymphocyte subpopulations were evaluated using three main classifications: based on IgD / CD38 expression (classification Bm1-Bm5), co-expression of IgD / CD27 and CD38 / CD27. The statistical analysis of data was performed with STATISTICA Version 12.0 Inc. Method of discriminant analysis was performed to evaluate diagnostic utility of relative values of T- and B-cell subsets. Results In the discriminant model the top significance was documented while assessing the percentage of naive B-cells (Bm1, IgDdimCD38low), germinal center B-cells (Bm 3+Bm4, IgDlowCD38hi), naive B-cells (IgDdimCD27low), unswitched memory B-cells (IgDdimCD27dim), naive mature B-cells (CD27dimCD38low), transient B-cells (CD27lowCD38hi), all T-cells (CD3hi), Tregs (CD3hiCD4hiCD25hi), Tcyt (CD3hiCD8hi) and Th (CD3hiCD4hi), model percent correct was 78%, p &lt;0,05. The discriminant function was either f1 for distinguishing HVs versus ill patients SLE and pSS (all participants are accounted) or f2 for SLE versus pSS (only participants with disease are accounted). During ROC analysis, performed for the differential diagnosis of healthy and sick patients, this discriminant model had a sensitivity of 86,5% and a specificity of 72,8%, the area under the curve (AUC) 0.94, p &lt;0.001. Among the group of ill patients, the differential diagnosis between SLE and pSS had a sensitivity of 69,6% and specificity of 64,8%, AUC 0.87, p &lt;0.001. Graphic representation of the discriminant analysis is performed on Figure 1. The group of patients, meeting the criteria for both pSS and SLE, is between the main groups. Figure 1. Graphic distribution of SLE, pSS and pSS+SLE patients, as well as HVs analyzed by discriminant analysis. Conclusion T- and B-cell peripheral blood subsets might provide an additional diagnostic tool for distinction SLE, pSS and HVs. Differential diagnosis between pSS and SLE is difficult, because this diseases may coexist. References [1]Guillermo Carvajal Alegria, Pierre Gazeau1, Sophie Hillion et al. Could Lymphocyte Profiling be Useful to Diagnose Systemic Autoimmune Diseases? Clinic Rev Allerg Immunol (2017) 53:219–236 [2]Sandra Gofinet Pasoto, Victor Adriano de Oliveira Martins, Eloisa Bonfa. Sjögren’s syndrome and systemic lupus erythematosus: links and risks. Open Access Rheumatol. 2019; 11: 33–45. Disclosure of Interests None declared